For years, we’ve known that eating nuts is good for our ticker. In 2003, the Food and Drug Administration recommended that daily consumption of nuts as part of a low-fat diet may reduce the risk of heart disease.

Now a large observational study recently published in the New England Journal of Medicine (NEJM) found that people who ate a handful of tree nuts (about 1 ounce) each day reduced their risk of death by 20%, compared to those who avoided the snack.

Nuts are chock-full of nutrients and rich in unsaturated fatty acids, fiber, vitamins, minerals and many other healthy compounds, such as antioxidants and phytosterols (plant steroids that help lower cholesterol). Another study published this year in the NEJM, which involved persons at high risk of cardiovascular disease, showed a significant reduction in heart attacks and strokes among participants who followed a Mediterranean diet, supplemented with walnuts, hazelnuts and almonds.

Despite these positive findings, few studies have investigated nut consumption in relation to total mortality in a large study population. The NEJM study is the largest such study to date and has thrust the lowly nut square into the ongoing discussion about the health effects of various dietary choices.

Harvard University researchers analyzed data from two long-term studies involving health professionals. They examined the association between nut consumption and specific causes of mortality among more than 76,000 women in the Nurses’ Health Study, conducted from 1980 to 2010, and more than 42,000 men in the Health Professionals Follow-up Study, conducted between 1986 and 2010.

The two studies obtained repeated measures of diet and extensive data on health conditions. Nut consumption was obtained at baseline and updated every 2-4 years. Over the course of 30 years of follow-up, more than 27,000 deaths were recorded and then correlated with the health data that were collected over time.

When nut consumers were compared to people who never ate nuts, researchers found that the greater the frequency of eating nuts, the lower the risk of dying from any cause. Eating them once a week resulted in an 11% lower risk of death; 2-4 times per week had a risk drop of 13%; and those who had at least one serving per day reduced their overall risk of death by 20%.

Nut consumption also correlated with a lower risk of death due to cancer, heart disease and respiratory disease. And nut eaters were healthier overall with lower rates of obesity and lower cholesterol and blood sugar.

Keep in mind that this was a retrospective, observational study where researchers are limited to finding correlations between nut consumption and healthier outcomes. It takes a controlled, prospective study to draw a firm conclusion about cause and effect.

However, eating tree nuts (unless you have a nut allergy or other health restriction) seems a reasonable and healthful choice. Just remember that nuts are high in calories, so if you eat too much, the added pounds you pack on over time could diminish some of their health benefits.